The trend of contemporary medicine is towards less invasive and more localized therapy. Many routine treatments employed in modern clinical practice involve percutaneous insertion of needles and catheters for biopsy and drug delivery. The aim of a needle insertion procedure is to place the tip of an appropriate needle safely and accurately in a lesion, organ or vessel. Examples of treatments requiring needle insertions include vaccinations, blood/fluid sampling, regional anesthesia, tissue biopsy, catheter insertion, cryogenic ablation, electrolytic ablation, brachytherapy, neurosurgery, deep brain stimulation and various minimally invasive surgeries.
In general, complications of percutaneous needle insertion are due to poor technique and needle placement. Physicians and surgeons often rely only upon kinesthetic feedback from the tool that they correlate with their own mental 3-D perception of anatomic structures. However, this method has significant limitations since as the needle penetrates the tissue, the tissue deforms and thus, even when working with straight rigid needles the needle might miss the target. To improve needle placement, rigid needles can be maneuvered under image guidance. In some cases the problem remains that rigid needles lead to excessive, injurious pressure on tissues. In a number of prior art documents, such as in US Patent Application No. 2007/0016067 to R. J. Webster III et al, there are described the use of beveled tip needles which are displaced during progression through a tissue because of the lateral deflection force imparted on the bevel tip by the tissue as the needle is pushed therethrough. Steering is accomplished by rotating the needle such that the bevel is oriented to generate the desired lateral deflection.
An alternative approach to ensuring the success of percutaneous procedures is to employ thin and flexible needles. There are numerous advantages to using such needles. Less serious complications occur with fine (less than 1 mm) biopsy needles than with standard coarse needles. Furthermore, thinner needles cause less damage and, for instance, have been shown to reduce the likelihood of Post Dural Puncture Headache (PDPH) after spinal anesthesia; indeed, the relative risk of PDPH decreases with reduction of needle diameter. Moreover, flexible needles facilitate curved trajectories that can be desirable in order to avoid sensitive tissues, such as bone or blood vessels or sensitive nerves or organs which might lie between feasible entry points and potential targets. However, a major disadvantage to using thin flexible needles is that they are difficult to control. They have non-minimum phase behavior and do not lend themselves to intuitive (human) control.
Devising a method to predict flexible needle motion was first addressed by DiMaio et al. in the article entitled “Needle Steering and Model-Based Trajectory Planning”, published in Proceedings of Medical Image Computing and Computer-Assisted Intervention, Montreal, 2003, pp. 33-40, Springer. A limitation of this work is that due to the computation complexity, it does not allow for real-time simulation and control of the needle insertion.
In an article entitled “Flexible Needle Steering and optimal Trajectory Planning for Percutaneous Therapies”, published in Proceedings of Medical Image Computing and Computer-Assisted Intervention, Saint-Malo 2004, pp. 137-144 Springer, it was demonstrated by the inventors in the present application that the needle tip path is not unique and can be optimized to minimize lateral pressure of the needle body on the tissue.
The disclosures of each of the publications mentioned in this section and in other sections of the specification, are hereby incorporated by reference, each in its entirety.